The present invention relates a rotational apparatus that includes an electric appliance unit, which functions as at least one of an electric motor for driving a rotary shaft and a generator, and a power transmitting mechanism for transmitting power to the rotary shaft from a rotor that receives power from an external driver source.
In certain types of vehicles, the engine is automatically stopped when starting idling so that the fuel consumption is reduced. This operation is referred to as idling engine stop operation. For example, Japanese Laid-Open Utility Model Publication No. 6-87678 discloses a hybrid compressor, which performs air conditioning even if the idling engine stop operation is being executed. The hybrid compressor has an electromagnetic clutch located between a pulley and a rotary shaft. A belt receiving portion is formed in the periphery of the pulley. A motor is accommodated inside of the belt receiving portion. To actuate the compressor when the engine is running, the electromagnetic clutch is engaged. This permits the rotary shaft to receive rotational power from the engine through a belt engaged with the belt receiving portion, the pulley, and the clutch. To actuate the compressor when the engine is not running, the clutch is disengaged and the rotary shaft obtains rotational power from the electric motor.
An electromagnetic clutch has relatively large members such as electromagnets and is therefore disadvantageous in reducing the size and the cost of an entire compressor. To continue rotating a rotary shaft of a compressor even if an engine is not running, a one-way clutch may be used instead of the electromagnetic clutch. Providing a one-way clutch in the power transmission path between the pulley and the rotary shaft is more advantageous in reducing the size and the cost of the entire compressor than providing an electromagnetic clutch.
To provide a one-way clutch in the power transmission path between a pulley and a rotary shaft, a bearing needs to be provided between the pulley and the rotary shaft so that the pulley and the rotary shaft rotate with respect to each other. If great load acts on the bearing, the bearing needs to be large and have a great withstand load (a great rated load). A large bearing is disadvantageous in reducing the size and the cost of a rotational apparatus.
Accordingly, it is an objective of the present invention to provide a rotational apparatus that reduces the size and the cost when a one-way clutch is provided in the power transmission path between a rotor and a rotary shaft.
To achieve the foregoing and other objectives and in accordance with the purpose of the present invention, a rotational apparatus having a housing, a rotary shaft located in the housing, an electric appliance unit, and a power transmitting mechanism is provided. The electric appliance unit functions as at least one of an electric motor and a generator. The power transmitting mechanism transmits power from an external driver source to the rotary shaft via a rotor. When the electric appliance unit functions as the electric motor, the rotary shaft is rotated by electric current supplied to the electric appliance unit. When the electric appliance unit functions as the generator, the generator generates electricity as the rotary shaft rotates. The rotational apparatus includes a first rotation permitting mechanism, a one-way clutch, and a second rotation permitting mechanism. The first rotation permitting mechanism is located between the rotor and the rotary shaft to permit the rotor and the rotary shaft to rotate relative to each other. The one-way clutch is located between the rotor and the rotary shaft. The one-way clutch permits the rotary shaft to rotate in one direction relative to the rotor and prevents the rotary shaft from rotating in the other direction relative to the rotor. The second rotation permitting mechanism is located between the housing and the rotor to permit the rotor to rotate relative to the housing. Power transmitted from the external drive source to the rotor is transmitted to the rotary shaft via the one-way clutch. The rotor is supported by the housing with the second rotation permitting mechanism.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.